The present invention relates to disc drive data storage systems and, more particularly, to suspensions for supporting data recording heads.
Disc drive data storage systems use rigid discs which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor which causes the discs to spin and the surfaces of the discs to pass under respective disc head sliders. The sliders carry transducers which write information to and read information from the disc surfaces. The slider and transducer are often together referred to as a xe2x80x9cheadxe2x80x9d. Each slider is supported by an actuator arm and a suspension. The actuator arms move the sliders from track-to-track across the surfaces of the discs under the control of electronic control circuitry for track following operations.
The suspension connects the actuator arm to the slider. The suspension provides a preload force through a relatively rigid load beam which forces the slider toward the disc surface. Additionally, the suspension is flexible in the slider pitch and roll directions to allow the slider to follow the topography of the disc. This pitch and roll flexibility is obtained from a gimbal or flexure structure, which can be integral with the load beam or a separate piece part that is welded or otherwise attached to the load beam.
The slider includes a hydrodynamic (e.g., air) bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to fly above or in close proximity to the disc surface.
One of the problems associated with disc drive operation is Non-Repeatable Runout (NRRO) of the Head-Gimbal Assembly (HGA). An important contributor to NRRO of the HGA is slider off-track motion caused by asymmetry in the first bending mode of the HGA. The first bending mode is bending in a direction normal to the disc surface. During manufacture and assembly of the HGA, process tolerances often lead to minor variations in the roll static angle (RSA) of the slider from a desired RSA. These variations are reduced by adjusting the RSA with an adjustment tool. However, these adjustments can lead to asymmetry in the first bending mode of the HGA. Detailed testing has shown a direct correlation between the magnitude of adjustments to the RSA of the slider and HGA NRRO. As the magnitude of the RSA adjustments increases, the off-track component of the first bending mode of the HGA becomes larger, which results in an increased contribution to the NRRO.
One solution to the HGA NRRO problem is to decrease the magnitudes of allowable adjustments to the RSA and to use an improved RSA adjustment tool. However, as the number of tracks per inch and the disc rotational velocities continue to increase in newer disc drive products, the performance requirements within the drive have become more strained. This has caused drastically increased sensitivities within the drive. As a result, the existing solution of limiting the RSA adjust is no longer effective in decreasing NRRO contributions from the suspension.
The present invention provides a solution to this and other problems and offers other advantages over the prior art.
One aspect of the present invention relates to a disc drive suspension which includes a longitudinal axis, a rigid load beam section and a preload transfer section. The rigid load beam section extends along the longitudinal axis and has first and second opposing lateral side edges with respective first and second stiffening rails. The first and second stiffening rails are bent out-of-plane with respect to a main body portion of the rigid load beam section and terminate at a distal end of the rigid load beam section. The preload transfer section extends distally from the distal end of the rigid load beam section and has a third stiffening rail. The third stiffening rail is bent out-of-plane with respect to a main body portion of the preload transfer section and extends longitudinally from the distal end of the rigid load beam section.
Another aspect of the present invention relates to a disc drive suspension which includes an elongated suspension body that is formed of a single, continuous piece of material. An actuator mounting aperture extends through a proximal end of the suspension body and has a center. A load point is located near a distal end of the suspension body. The suspension body has a length of 0.6 inches to 0.7087 inches from the center of the proximal actuator mounting aperture to the load point, a mass of 40 milligrams to 45 milligrams, a spring rate of 30 gram-force per inch (gmf/in.) to 35 gmf/in., and a first bending mode frequency of at least 2.5 kHz.
Another aspect of the present invention relates to a disc drive suspension which includes first and second stiffening rails extending along opposing lateral side edges of the suspension and terminating prior a distal end of the suspension, and stiffening means formed in the suspension for increasing a stiffness of the suspension distally from the first and second stiffening rails.